Genome-wide Association Analysis Of Salt Tolerance At Germination Stage In Spring Wheat

Wheat is one of the worlds three major food crops.Salt stress is one of the main abiotic stress factors affecting crop yield and quality.Studying the relationship between wheat germination related traits and salt tolerance,screening salt tolerant wheat germplasm resources and salt tolerance related gene loci can provide reference and basis for wheat salt tolerance breeding.In this study,259 spring wheat varieties were used as materials,and 200 mmol L^-1Na Cl solution was used to simulate salt stress environment.The salt tolerance of 259 spring wheat germplasm resources during indoor germination was evaluated.The longest root length,seedling height,root number,coleoptile,root fresh weight,seedling fresh weight,root dry weight,seedling dry weight,germination potential and germination rate were measured.The membership function method was used to identify the salt tolerance of 259 spring wheat,and the correlation analysis,principal component analysis and membership function method were used to identify the salt tolerance of 259 spring wheat.Genome-wide association analysis of259 spring wheat samples was performed using 55K gene chip,which provided the basis for salt tolerance gene mining and molecular marker-assisted selection of wheat.The main results were as follows:1.Correlation analysis:Salt tolerance of wheat is a complex quantitative trait.Among them,relative root fresh weight and relative root dry weight,relative germination potential and relative germination rate are all significantly positively correlated,with the highest correlation coefficient（0.909 and 0.881,respectively）.2.Principal component analysis:The principal component analysis was used to conduct factor analysis on 10 germination traits.The results showed that the first factor:seedling fresh weight and seedling dry weight had the highest correlation,and the correlation coefficients were 0.87 and 0.782,respectively.The seedling fresh weight,seedling dry weight,root fresh weight,root dry weight and seedling height could be used as important indicators for identification and comprehensive evaluation of salt tolerance in wheat germination.3.Membership function analysis showed that spring wheat（Xinjiang）had the best salt tolerance performance,D value reached 0.86,red spring wheat,barley and barley and other six materials had good salt tolerance performance,D value reached more than 0.80,Atri 3890/Skl had the worst salt tolerance performance,D value was 0.24,Purple S556,Cnt 1 had poor performance,D value was below 0.3.4.The Q+K mixed linear model was used to conduct genome-wide association analysis of 259 spring wheat varieties by combining the phenotypic traits,relative values of phenotypic coefficients and comprehensive evaluation values under normal and salt stress conditions,and the 55K gene chip was used to obtain 405 SNP loci significantly associated with germination traits.Among them,272 loci were significantly associated with germination traits under normal conditions,and the contribution rate was4.30%-13.14%.Under salt stress,133 loci were significantly associated with germination traits,accounting for 4.29%-10.78%.They were distributed on 21 chromosomes of wheat,and 153 SNPs were significantly associated with salt tolerance,accounting for 4.36%-10.10%.Twelve SNP loci significantly associated with the comprehensive evaluation value of salt tolerance were obtained,which were located on chromosomes 1A,1B,2A,3A,4A,4B,5A,5B,6A and 7A,respectively,with the contribution rate of4.44%–11.65%.The SNP markers associated with salt tolerance during wheat germination were searched in the Chinese Spring Genome Database of Common Wheat to screen candidate genes.A total of 17candidate genes related to germination traits,such as Traes CS2D01G509800,Traes CS5A01G403700,Traes CS7B01G473400,were obtained.These genes correspond to receptor-like protein kinase,cold-inducible protein,catalase and other functions.